That points towards an issue either with the cluster or the connection from the engine ECU.But engine right on high rpm. Car starts to stall when accelerating. Maybe I should start with (crank and/or cam sensor)?
The dash is the one major difference between the Catera and Omega, and without seeing behind the cluster there may be additional wiring/plugs for the extra displays/warnings.
I suspect that the alternator only feeds the charge light (and battery voltage gauge), whereas the rpm signal comes from the engine ECU information (crank and/or cam sensor).
If the pedal trick works*, any codes may highlight a discrepancy.
* It should as the car is DBW.
The speedometer issue is almost guaranteed to be unrelated.
Previous owner said that they changed crank sensor from omega.
Fuel filter ok?
if it miss fires on acceleration that points to ignition voltage and coil packs